Turbine bucket with cast-in insert



May 7, 1958 J. R. HAYES 2,836,391

TURBINE BUCKET WI H CAST-IN INSERT Filed Oct. 10, 1951 IN V EN TOR Unitfid States Patent o TURBINE BUCKET WITH CAST-IN INSERT John R. Hayes, Indianapolis, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application October 10, 1951, Serial No. 250,663

4 Claims. (Cl. 253-3945) My invention relates to turbine blades or buckets and the like, and primarily to a bucket particularly adapted In view of the high temperature of the gas stream in gas turbines and the desirability of increasing the tolerance of the turbine for high temperatures, many proposals for cooling the nozzles, vanes, and buckets of gas turbines have been advanced. One approach to the problem involves the use of hollow blades (by which term such elements as nozzles, stator vanes, and turbine rotor blades or buckets are intended) with circulation of a cooling medium such as air through the blade.

With such hollow blades, the rate of heat transfer from the wall of the blade to the air stream flowing through the blade is much lower than would be desirable. My invention contemplates the provision in the passage through a hollow blade of radiating fins bonded to the wall of the blade which will greatly increase the heat transfer surface and thereby greatly improve the cooling of the blade.

In its preferred form, the blade of the invention comprises a cast body which may be similar in external form to conventional known turbine buckets, the form of the blade and root being whatever is most suitable to the particular installation. The cast bucket is hollow and contains therein, in intimate relationship to the interior to the blade, a metal liner which defines a passage through the blade for cooling air and is formed with radiating fins extending across the internal passage to improve the heat transfer characteristics of the blade. Intimate contact between the blade and the liner is assured by casting the blade around the liner, which has the additional advantage that the liner serves as a core for the casting of the hollow bucket. The metal liner is of a high degree of dimensional stability and facilitates the casting of a hollow bucket with walls of high dimensional accuracy.

The principal objects of the invention are to improve the performance of gas turbines, to improve turbine buckets, and to provide cast hollow turbine buckets.

The preferred manner in which these objects are realized will be more readily apparent to those skilled in the art from the succeeding detailed description of preferred embodiments of the invention.

Referring to the drawings: Figure l is a side view of a turbine bucket according to the invention, with parts cut away, shown as mounted in a fragmentary portion of a turbine rotor; Figure 2 is a longitudinal sectional view of the same taken on the plane indicated by 2-2 in Figure 1; Figure 3 is a transverse section of the same taken on the plane indicated by 3--3 in Figure 1; and Figure 4 is a transverse section similar to that of Figure 3 illustrating a modified form of the invention.

In Figures 1 and 2 the blade or bucket B of the invention is illustrated as mounted in a turbine wheel or rotor R, only a portion of the rim of which is shown.

Patented May 27, 1958 The bucket comprises a blade portion with walls 12 and 13 of any desired form, the airfoil configuration most clearly shown in Figure 3 being typical of buckets for certain applications. The blade portion if) is integral with a root or base portion 15 which may be provided with dovetail grooves or any other suitable arrangement for mounting the bucket on the rotor R.

Within the cast body 12, 13, 15 is a liner indicated generally as 2% which is of generally tubular form such as to be rather uniformly spaced from the outer surface of the blade portion and is in intimate engagement with the inner surface of the body. Preferably, the walls 12 and 13 taper from the root of the blade toward the tip. The liner 29, which is formed of thin sheet metal, may be made by known techniques of forming from a sheet or a tube. Mounted within the liner 2t) and extending through the blade portion of the bucket is a corrugated or zigzag sheet or strip 21, the convolutions of which engage alternately the walls of the liner 20. The strip 21, which provides heat radiating fins, may be inserted after the liner is formed or before the sheet from which liner 2% is formed is folded over and is brazed or spotwelded to the liner. Brazing, of course, assures better heat transfer between the liner 20 and the strip 21 which serves to increase the heat radiation surface of the liner. After the liner is fabricated, it is fitted as a core in a mold into which the metal is poured to form the body of the blade around the liner. It will be understood that the liner may extend beyond the blade and may be cut off during the finishing of the cast bucket. Thus, the liner not only serves as a core during the manufacture of the bucket but is retained to increase the heat radiating surface exposed to air or other cooling medium circulated through the blade. Air may be supplied to the internal passage of the bucket in any suitable manner as by the passage 31 through the rim of the Wheel R illustrated in Figures 1 and 2 and may flow through the blade past the walls of the liner and the cooling fins 22 formed by the strip 21; that is, the portions of the strip extending across the passage.

Since the blade is cast around the liner, intimate contact and good heat transfer from the blade to the liner are assured. I

Figure 4 illustrates a modification of the invention involving the same principles. In the form of Figure 4 the liner 2% may be similar to that of liner 20 of Figure 3 but the radiating fins are formed by a number of strips 23 extending between the walls of the liner and brazed or spot-welded thereto.

As will be apparent, the liner, particularly in view of the fins or transverse member 22 or 23 therein, contributes significantly to the stillness and strength of the bucket in addition to aiding the cooling thereof.

The detailed description herein of preferred embodiments of the invention for the purpose of explaining the principles thereof is not to be considered as limiting the scope of the invention, since many modifications thereof may be devised by the exercise of skill in the art within the scope of the invention.

I claim:

1. As an article of manufacture, a turbine bucket or the like comprising a liner of flattened tubular form with heat radiating fins defined by a corrugated strip extending between the walls thereof and a body disposed around the liner, the body comprising a blade portion and a base portion, the liner extending through the blade portion and base portion, and the outer surface of the liner being in intimate engagement with the inner surface of the body.

2. As an article of manufacture, a turbine bucket or the like comprising a liner of flattened tubular form with heat radiating fins defined by a corrugated strip extending between the walls thereof and a body 'disposed'around "a 1 =the coolant conduit, 'the major portion of the surface-of the .linerand bonded thereto, the body comprising the said passage Within the blade portion being in intimate blade portion and the base portion of the bucket. engagement with the outer surface of the liner.

3. A turbine bucketor the like comprising a metallic V r body having a passage Xtfin i g l 'gil h ody 8 l n 5 References Cited in the file ofthis' patent Wlll'lllllh body, the liner being tnbular so as to dennea V a V UNITED STATES PATENTS coolant therethrough, and a corrugatedetrip extending a i 7 between the Walls of the liner and bonded'theretorpro, 853,334 Backstmm May 14, 1907 viding heat radiating 'fins extending from the Wall of the 11956404 Noack :July "1934 liner across'rthe coolant conduit, the major portion of the 2'470J26 Altol'fel' t May tsurfaceof said passage being in intimate engagement with L 3' Q -*v- R 1930. the outer surface of the liner, 7 V V I 213201373 :Pnce k 1950 4. A turbine bncketor the like comprising a metallic 2,641,040 Goddard June 1953 body; the body includinga fluid-directing blade portion 2,656,146 sonmger l-V-'V.:-- L 1953 and having a passageextending longitudinally of the body 15 r 2,687,278

Smith' Aug 24, 1954 Within the bladeportion thereof, a linerwithin the body, e

the liner being tubular so as to define a coolant conduit FOREIGN P V therethrough, and a corrugated strip extending between 602,530 Great Britain May 28, 1948 the Walls of the liner and bonded thereto providing heat a 625,693 Great Britain July 1, 1949 radiating fins extending from the wall of the liner across 20 r I a V r H UNITED STATES PATENT TTTQT CERTIFIQATE UT QQRECEGN Patent No, 2,836,391 May 27, 1958 John R Hayes It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 3, line 7, after "coolaumb insert conduit Signed and sealed this 25th day of November 1958,

(SEAL) Attest:

KARL H1, AJGLINE RGBER'T C; WATSON Attesting Oflicer Commissioner of Patents 

